Will Australia be drawn into a fresh conflict in the Middle East?

Is Australia about to be drawn into another military conflict alongside the United States in the Middle East?

What we don't know yet is whether this is a one-off, punitive strike to deter further chemical attacks on civilians or the start of a longer process to remove Bashar al-Assad, the Syrian dictator.

We've learnt something remarkable about Donald Trump here. The man who has promoted "America first" and shown mostly hard-headed realism on international affairs has abruptly launched a humanitarian intervention.

Mr Trump notably called "on all civilised nations to join us in seeking to end the slaughter and bloodshed in Syria [and] to end terrorism of all kinds and all types".

Is he planning to go further? To intervene fully in Syria and remove Mr Assad while forcefully brokering some kind of stable peace?

Notwithstanding Mr Trump's strong words and those of US Secretary of State Rex Tillerson in the past 24 hours, removing Mr Assad remains just as tangled a proposition as it has at any time in the past couple of years during which it has eluded the international coalition.

There are no signs that Russia is prepared to abandon its ally Assad, meaning that the US would be taking on a major power. Unless Trump has some sway over Moscow we don't know about, then ending the slaughter and bloodshed in Syria would mean a major military intervention requiring air power and ground troops, including Australia's.

The sheer magnitude of that means it is more likely that the US military action will remain a limited strike to punish Assad over the chemical attack. Mr Trump is finally responding to the crossing of the famous red line that his predecessor had drawn but then failed to enforce. He is saying that he will not hold all the might of the US military on a tight leash when there are such deliberate and cruel provocations.

Russia, importantly, can at least tolerate this limited attack on its ally Assad. If Moscow is prepared to let it pass and Assad has no way to retaliate against the US, this should not escalate the broader conflict.

And if the US plans to constrain its military response to such targeted strikes, there is no role for Australia.

But remember this is a complicated conflict and Mr Trump has just proved himself to be an unpredictable president. Even if it is meant as a limited strike, the X-factor is that someone will decide to hit back somehow - Assad through some indirect means, Russia by deliberately conflicting with coalition air forces operating in Syria, or Iran perhaps through its proxy Hezbollah.

If Mr Trump was prepared to act so swiftly and decisively over the chemical attack, he may well do the same again if the other side takes the next step. Then we are in an escalation and Australia would be hard pressed to avoid getting involved.